Studies: Drilling is causing quakes

Scientists say jolts can trigger more dangerous shifts

Published 10:45 pm, Thursday, April 23, 2015

With the evidence coming in from one study after another, scientists are now more certain than ever that oil and gas drilling is causing hundreds upon hundreds of earthquakes across the U.S.

So far, the quakes have been mostly small and have done little damage beyond cracking plaster, toppling bricks and rattling nerves. But seismologists warn that the shaking can dramatically increase the chances of bigger, more dangerous quakes.

Up to now, the oil and gas industry has generally argued that any such link requires further study. But the rapidly mounting evidence could bring heavier regulation down on drillers and make it more difficult for them to get projects approved.

He said companies and states can reduce the risk by taking such steps as monitoring operations more closely, imposing tighter standards and recycling wastewater from drilling instead of injecting it underground.

A series of government and academic studies over the past few years — including at least two reports released this week alone — has added to the body of evidence implicating the U.S. drilling boom that has created a bounty of jobs and tax revenue over the past decade or so.

On Thursday, the U.S. Geological Survey released the first comprehensive maps pinpointing more than a dozen areas in the central and eastern U.S. that have been jolted by quakes that the researchers said were triggered by drilling. The report said man-made quakes tied to industry operations have been on the rise.

Scientists have mainly attributed the spike to the injection of wastewater deep underground, a practice they say can activate dormant faults. Only a few cases of shaking have been blamed on fracking, in which large volumes of water, sand and chemicals are pumped into rock formations to crack them open and free oil or gas.

"The picture is very clear" that wastewater injection can cause faults to move, said USGS geophysicist William Ellsworth.

Until recently, Oklahoma — one of the biggest energy-producing states — had been cautious about linking the spate of quakes to drilling. But the Oklahoma Geological Survey acknowledged it is "very likely" that recent seismic activity was caused by the injection of wastewater into disposal wells.

The Environmental Protection Agency said there no plans for new regulations as a result of the USGS study.